An endoscope system includes an illumination section, a color component ratio measurement section and a light quantity ratio adjustment circuit. The illumination section including a light source sequentially or simultaneously radiates an illumination light being a plurality of narrow-band lights having wavelengths different from each other and having light quantities which are independently controllable each other, on an observation object. The color component ratio measurement section measures a color component ratio of the illumination light. The light quantity ratio adjustment circuit adjusts a light quantity ratio of the narrow-band lights based on an output from the color component ratio measurement section and performs color correction to cause the illumination light to be a desired color.